The invention relates to a reagent reservoir for fluids as part of a microfluidic flow cell for the analysis and/or synthesis of substances or as a separate module, comprising a storage chamber connected to a channel for conveying fluid out of, into and/or through the storage chamber, the channel having a channel area which is delimited by a substrate and by a film connected to the substrate and in which the channel is closed and can be opened at a predetermined breaking point by deflection of the film, said film connected to the substrate also delimiting the storage chamber in addition to the channel area.
A reagent container of this kind is disclosed in WO 2009/0710781 A1. The storage chamber of this known reagent reservoir is formed by a thermoformed area of the film which delimits the channel area and is otherwise plane. The film is composed of an aluminum layer with a plastic coating directed toward the inside of the storage chamber. Outside the storage chamber and the channel area, and at the predetermined breaking point, the film is adhesively bonded and/or welded to a plane surface of the substrate or of a further film covering said surface.
The surface extent of the predetermined breaking point produced by welding and/or adhesive bonding between the plastic coating of the film and the plane surface of the substrate can only be predefined with difficulty. Variations result especially from the behavior of the plastic coating of the film during welding, the distribution of the temperature generated by a welding tool, the attainable width of the weld path of ca. 1 mm, the positioning accuracy of the welding tool, and therefore the reproducibility of the distance of the predetermined breaking point from the storage area. Correspondingly, the forced needed to break open the predetermined breaking point also varies undesirably.